Grinding wheels
 

Last weekend, I got new tires and a realignment, and everything was great. The next day, I noticed that the town put new speed humps on Main Street, but not until I was on top of one at full speed. (They've since put up "raised sidewalk" signs.)

Since then, though, something near both of my front wheels has been intermittently grinding. Curiously, braking, steering, alignment, and handling are not affected one bit. Tires are too new to notice any abnormal wear patterns. Last I checked, I had a decent amount of brake pad left, and wasn't getting any "replace me!" squealing beforehand.

Turning and cornering don't change the sound much, if at all. If I apply the brakes, I hear a weird sound from my front passenger-side brake that sounds a little bit like whispering (psst-psst-pssst-pssst-psssst-psssst) as I slow down.

It mostly happens at lower speeds, but once I hit about 40 mph, it either goes away or is drowned out by wind noise until it decides to start doing it again. It's most noticeable when coming to a stop while going downhill.

My guess is that I finished off the wheel bearings, but if I were so sure, I wouldn't be asking you guys.

I had a noise like that for several years and could not find the cause until I had to change the axle shafts due to torn CV boots, after which the noise went away. I doubt going over a speed bump could cause that though. If you think it might be a bearing, jack the front end up and feel for play in the wheels.

You could also take it back to the place that did the wheel alignment and tell them it never made this noise until after they worked on it. They probably wouldn't charge to take a look and see what the problem is.

Update, before I forget! On the noisy passenger side, the outer pad is completely gone, and the rotor is terribly scored. On the other side, everything looks great, almost new. Either I warped that rotor, or the caliper is on the way out (which wouldn't surprise me; it's the original one).

The noise is a combination of me running out of brake pad on that wheel, and the anti-lock system seeing that one wheel going too fast and kicking on the ABS.

I can't tell if ramming that bump caused this, or if it was happening for a long time, and the bump and noise are just coincidental, but I'm going to play it safe and order a new caliper tomorrow.

Are the two front calipers the same, or do I specifically need a front right caliper?

The caliper slide pins are probably seized. These are the bolts that anchor the caliper at the top and bottom of the caliper, and are only threaded for the first inch or so. The rest of the pin allows the caliper to slide and keep equal pressure on the inner and outer pads. When you have the pin/bolts out, clean them, clean out the hole they ride in, and make sure it is properly greased.

You don't necessarily need new calipers.

Rockauto is showing 2 different part numbers for the L and R calipers.